U.S. patent number 7,895,645 [Application Number 12/120,000] was granted by the patent office on 2011-02-22 for multiple user credentials.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Smita Bodepudi, Medha Dinesh Date, Murali Neralla, Prasad Venkata Potluri.
United States Patent |
7,895,645 |
Bodepudi , et al. |
February 22, 2011 |
Multiple user credentials
Abstract
A login shell and file/directory access checking supporting
multiple user credentials are provided. The login shell receives
user input from a particular user including login information for a
plurality of user accounts for that particular user. The login
shell authenticates the plurality of user accounts using the login
information and retrieves a plurality of user credentials
corresponding to the plurality of user accounts. This plurality of
user credentials forms a multi-user credential. In response to a
request for access to a file, the access rights to the file for the
user are verified by verifying the access rights of the multi-user
credential.
Inventors: |
Bodepudi; Smita (Austin,
TX), Date; Medha Dinesh (Austin, TX), Neralla; Murali
(Austin, TX), Potluri; Prasad Venkata (Austin, TX) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
|
Family
ID: |
37680507 |
Appl.
No.: |
12/120,000 |
Filed: |
May 13, 2008 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20080256609 A1 |
Oct 16, 2008 |
|
Related U.S. Patent Documents
|
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
11186673 |
Jul 21, 2005 |
|
|
|
|
Current U.S.
Class: |
726/5; 726/4 |
Current CPC
Class: |
G06F
21/6218 (20130101); G06F 21/41 (20130101) |
Current International
Class: |
H04L
29/06 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Shockley, Identification and Authentication when Users have
Multiple Accounts, ACM, 1993, pp. 185-191. cited by
examiner.
|
Primary Examiner: Dinh; Minh
Attorney, Agent or Firm: Yee & Associates, P.C. Baca;
Matthew W.
Parent Case Text
This application is a continuation of application Ser. No.
11/186,673, filed Jul. 21, 2005, status pending.
Claims
What is claimed is:
1. A computer implemented method for supporting multiple user
credentials, the method comprising: receiving user input from a
given user including login information for a plurality of user
accounts for the given user; authenticating, by a processor, the
plurality of user accounts based on the login information;
retrieving a plurality of credentials for the plurality of user
accounts to form a multi-user credential; and responsive to a
request for access to a file, verifying access rights to the file
by verifying access rights of the multi-user credential.
2. The method of claim 1, wherein the login information includes a
primary user identification, a primary password, a secondary user
identification, and a secondary password.
3. The method of claim 1, wherein the plurality of credentials
include a primary user identification, a primary group
identification, a secondary user identification, and a plurality of
secondary group identifications.
4. The method of claim 3, wherein verifying the access rights of
the multi-user credential includes: comparing the primary user
identification to a file owner identification associated with the
file; and responsive to the primary user identification matching
the file owner identification associated with the file, providing
access to the file based on permissions associated with the file
owner identification.
5. The method of claim 4, wherein verifying the access rights of
the multi-user credential further includes: responsive to the
primary user identification not matching the file owner
identification associated with the file, comparing the secondary
user identification with the file owner identification associated
with the file; and responsive to the secondary user identification
matching the file owner identification associated with the file,
providing access to the file based on permissions associated with
the file owner identification.
6. The method of claim 5, wherein verifying the access rights of
the multi-user credential further includes: responsive to the
secondary user identification not matching the file owner
identification associated with the file, comparing the primary
group identification with the file group identification associated
with the file; and responsive to the primary group identification
matching the file group identification associated with the file,
providing access to the file based on permissions associated with
the file group identification.
7. The method of claim 6, wherein verifying the access rights of
the multi-user credential further includes: responsive to the
primary group identification not matching the file group
identification associated with the file, comparing the plurality of
secondary group identification with the file group identification
associated with the file; and responsive to one of the plurality of
secondary group identifications matching the file group
identification associated with the file, providing access to the
file based on permissions associated with the file group
identification.
8. The method of claim 1, wherein access includes execution.
9. The method of claim 8, wherein execution takes place on a remote
data processing system.
10. A computer program product comprising: a non-transitory
computer usable medium including computer usable program code for
supporting multiple user credentials, said computer program product
including: computer usable program code for receiving user input
from a given user including login information for a plurality of
user accounts for the given user; computer usable program code for
authenticating the plurality of user accounts based on the login
information; computer usable program code for retrieving a
plurality of credentials for the plurality of user accounts to form
a multi-user credential; and computer usable program code,
responsive to a request for access to a file, for verifying access
rights to the file by verifying access rights of the multi-user
credential.
11. The computer program product of claim 10, wherein the login
information includes a primary user identification, a primary
password, a secondary user identification, and a secondary
password.
12. The computer program product of claim 10, wherein the plurality
of credentials include a primary user identification, a primary
group identification, a secondary user identification, and a
plurality of secondary group identifications.
13. The computer program product of claim 12, wherein the computer
usable program code for verifying access rights to the file by
verifying the access rights of the multi-user credential includes:
computer usable program code for comparing the primary user
identification to a file owner identification associated with the
file; and computer usable program code, responsive to the primary
user identification matching the file owner identification
associated with the file, for providing access to the file based on
permissions associated with the file owner identification.
14. The computer program product of claim 13, wherein the computer
usable program code for verifying access rights to the file by
verifying the access rights of the multi-user credential further
includes: computer usable program code, responsive to the primary
user identification not matching the file owner identification
associated with the file, for comparing the secondary user
identification with the file owner identification associated with
the file; and computer usable program code, responsive to the
secondary user identification matching the file owner
identification associated with the file, for providing access to
the file based on permissions associated with the file owner
identification.
15. The computer program product of claim 14, wherein the computer
usable program code for verifying access rights to the file by
verifying the access rights of the multi-user credential further
includes: computer usable program code, responsive to the secondary
user identification not matching the file owner identification
associated with the file, for comparing the primary group
identification with the file group identification associated with
the file; and computer usable program code, responsive to the
primary group identification matching the file group identification
associated with the file, for providing access to the file based on
permissions associated with the file group identification.
16. The computer program product of claim 15, wherein the computer
usable program code for verifying access rights to the file by
verifying the access rights of the multi-user credential further
includes: computer usable program code, responsive to the primary
group identification not matching the file group identification
associated with the file, for comparing the plurality of secondary
group identification with the file group identification associated
with the file; and computer usable program code, responsive to one
of the plurality of secondary group identifications matching the
file group identification associated with the file, for providing
access to the file based on permissions associated with the file
group identification.
17. A data processing system for supporting multiple user
credentials, the data processing system comprising: a bus system; a
communications system connected to the bus system; a memory
connected to the bus system, wherein the memory includes computer
usable program code; and a processing unit connected to the bus
system, wherein the processing unit executes the computer usable
program code to: receive, using a login shell, user input from a
given user including login information for a plurality of user
accounts for the given user and authenticates the plurality of user
accounts based on the login information; retrieve, using an
operating system component, a plurality of credentials for the
plurality of user accounts to form a multi-user credential; and
verify, using a file access checking component, access rights to
the file by verifying access rights of the multi-user
credential.
18. The data processing system of claim 17, wherein the login
information includes a primary user identification, a primary
password, a secondary user identification, and a secondary
password.
19. The data processing system of claim 17, wherein the plurality
of credentials include a primary user identification, a primary
group identification, a secondary user identification, and a
plurality of secondary group identifications.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a data processing
system and, in particular, to a method, system, and computer
program product for supporting multiple user credentials.
2. Description of the Related Art
Currently, whenever any user is logged into a multi-user or network
environment, such as AIX or Windows, the loggin shell or
environment allows for only one set of user credentials. That is,
one user identification (ID), one primary group ID, and one or more
secondary group IDs.
A problem arises when a user has more than one user account on a
system, user1 and user2, for instance. The problem is that when the
user is logged in under one account, user1, the user may only
access a file if user1's credentials allow access, regardless of
whether or not user2's credentials allow access to that file.
Therefore, if a file has only been granted access for a user with
user2's credentials, the user is not able to access that file while
logged in as user1, even though user2 is also the user's
account.
For example, on an AIX system, when a user, say aixuser1, is logged
in, the logged in shell has only one user credential, one user ID,
one primary group ID and one or more secondary group IDs. In the
above example, the user has two user accounts, aixuser1 and
aixuser2 and there are some files as follows:
-rw------- 1 aixuser1 staff 631365 June 14 13:56 peruser1.log
-rw------- 1 aixuser2 staff 631365 June 14 13:56 peruser2.log
-rw------- 1 aixuser3 staff 631365 June 14 13:56 peruser3.log
The user cannot access both the files that he has permission to use
from a one user credential environment when logged in as
aixuser1.
The same is true under a windows environment. When a user is logged
in to a Windows environment, the logged environment has only one
user credential and one or more group credentials based on the
group memberships. The same example mentioned above for the AIX
environment also applies to the Windows environment.
Presently, there are three ways to get around these restrictions,
but none of these solutions is very satisfactory or efficient. One
solution is to create a new group consisting of the two user IDs
and set the file's group ID as the newly created group. However,
this solution is not practical, because the user needs to be a
system administrator to create groups or to change group
memberships.
Another solution is to use access control lists (ACLs) to provide
access to the second user ID. Every time user1 creates a new file,
user1 needs to grant ACL access to user2 and vice-versa. However, a
problem arises when the user's IDs change. For example, user2 gets
assigned to another user and the user gets assigned a new user ID
of user3. Now all the files and directories owned by user1 with ACL
access to user2 need to be found and have the ACL access changed to
user3 so that the files and directories owned by user1 are secured
from user2. Additionally, files and directories that used to belong
to user2 may also need to be found and altered.
Another solution is to login as user1, work with the files owned by
user1, then logout and login as user2 and work with the files owned
by user2. This solution is not very practical as all the files
cannot be accessed from one login shell or environment.
SUMMARY OF THE INVENTION
The present invention provides a method, system, and computer
program product for supporting multiple user credentials. In the
present invention, the method begins by receiving user input from a
particular user including login information for a plurality of user
accounts for that particular user. The plurality of user accounts
is authenticated using the login information. A plurality of user
credentials corresponding to the plurality of user accounts is
retrieved. This plurality of user credentials forms a multi-user
credential. In response to a request for access to a file, the
access rights to the file for the user are verified by verifying
the access rights of the multi-user credential.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features believed characteristic of the invention are set
forth in the appended claims. The invention itself, however, as
well as a preferred mode of use, further objectives and advantages
thereof, will best be understood by reference to the following
detailed description of an illustrative embodiment when read in
conjunction with the accompanying drawings, wherein:
FIG. 1 is a pictorial representation of a network of data
processing systems in which exemplary aspects of the present
invention may be implemented;
FIG. 2 is a block diagram of a data processing system that may be
implemented as a server, in accordance with illustrative
embodiments of the present invention;
FIG. 3 is a block diagram of a data processing system in which
exemplary aspects of the present invention may be implemented;
FIG. 4 is a pictorial representation of a login screen in
accordance with an exemplary embodiment of the present
invention;
FIG. 5 is a block diagram of a login system in accordance with an
exemplary embodiment of the present invention;
FIG. 6 is a block diagram that illustrates communicating a remote
command between two data processing systems in accordance with an
exemplary embodiment of the present invention;
FIG. 7 is a flowchart of a method for checking file/directory
access in accordance with an exemplary embodiment of the present
invention; and
FIG. 8 is a flowchart of a method for executing a command on a
remote data processing system in accordance with an exemplary
embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
FIGS. 1-3 are provided as exemplary diagrams of data processing
environments in which exemplary aspects of the present invention
may be implemented. It should be appreciated that FIGS. 1-3 are
only exemplary and are not intended to assert or imply any
limitation with regard to the environments in which the present
invention may be implemented. Many modifications to the depicted
environments may be made without departing from the spirit and
scope of the present invention.
With reference now to the figures, FIG. 1 depicts a pictorial
representation of a network of data processing systems in which
exemplary aspects of the present invention may be implemented.
Network data processing system 100 is a network of computers in
which the present invention may be implemented. Network data
processing system 100 contains a network 102, which is the medium
used to provide communications links between various devices and
computers connected together within network data processing system
100. Network 102 may include connections, such as wire, wireless
communication links, or fiber optic cables.
In the depicted example, server 104 connects to network 102 along
with storage unit 106. In addition, clients 108, 110, and 112
connect to network 102. These clients 108, 110, and 112 may be, for
example, personal computers or network computers. In the depicted
example, server 104 provides data, such as boot files, operating
system images, and applications to clients 108-112. Clients 108,
110, and 112 are clients to server 104. Network data processing
system 100 may include additional servers, clients, and other
devices not shown.
In the depicted example, network data processing system 100 is the
Internet with network 102 representing a worldwide collection of
networks and gateways that use the Transmission Control
Protocol/Internet Protocol (TCP/IP) suite of protocols to
communicate with one another. At the heart of the Internet is a
backbone of high-speed data communication lines between major nodes
or host computers, consisting of thousands of commercial,
government, educational and other computer systems that route data
and messages. Of course, network data processing system 100 also
may be implemented as a number of different types of networks, such
as for example, an intranet, a local area network (LAN), or a wide
area network (WAN). FIG. 1 is intended as an example, and not as an
architectural limitation for the present invention.
Referring to FIG. 2, a block diagram of a data processing system
that may be implemented as a server, such as server 104 in FIG. 1,
is depicted in accordance with an illustrative embodiment of the
present invention. Data processing system 200 may be a symmetric
multiprocessor (SMP) system including a plurality of processors 202
and 204 that connect to system bus 206. Alternatively, a single
processor system may be employed. Also connected to system bus 206
is memory controller/cache 208, which provides an interface to
local memory 209. I/O bus bridge 210 connects to system bus 206 and
provides an interface to I/O bus 212. Memory controller/cache 208
and I/O bus bridge 210 may be integrated as depicted.
Peripheral component interconnect (PCI) bus bridge 214 connects to
I/O bus 212 provides an interface to PCI local bus 216. A number of
modems may be connected to PCI local bus 216. Typical PCI bus
implementations will support four PCI expansion slots or add-in
connectors. Communications links to clients 108-112 in FIG. 1 may
be provided through modem 218 and network adapter 220 connected to
PCI local bus 216 through add-in connectors.
Additional PCI bus bridges 222 and 224 provide interfaces for
additional PCI local buses 226 and 228, from which additional
modems or network adapters may be supported. In this manner, data
processing system 200 allows connections to multiple network
computers. A memory-mapped graphics adapter 230 and hard disk 232
may also be connected to I/O bus 212 as depicted, either directly
or indirectly.
Those of ordinary skill in the art will appreciate that the
hardware depicted in FIG. 2 may vary. For example, other peripheral
devices, such as optical disk drives and the like, also may be used
in addition to or in place of the hardware depicted. The depicted
example is not meant to imply architectural limitations with
respect to the present invention.
The data processing system depicted in FIG. 2 may be, for example,
an IBM eserver.TM. pSeries.RTM. computer system, running the
Advanced Interactive Executive (AIX.RTM.) operating system or LINUX
operating system (eServer, pSeries and AIX are trademarks of
International Business Machines Corporation in the United States,
other countries, or both, while Linux is a trademark of Linus
Torvalds in the United States, other countries, or both).
With reference now to FIG. 3, a block diagram of a data processing
system is shown in which exemplary aspects of the present invention
may be implemented. Data processing system 300 is an example of a
computer, such as client 108 in FIG. 1, in which code or
instructions implementing the processes of the present invention
may be located. In the depicted example, data processing system 300
employs a hub architecture including a north bridge and memory
controller hub (MCH) 308 and a south bridge and input/output (I/O)
controller hub (ICH) 310. Processor 302, main memory 304, and
graphics processor 318 are connected to MCH 308. Graphics processor
318 may be connected to the MCH through an accelerated graphics
port (AGP), for example.
In the depicted example, local area network (LAN) adapter 312,
audio adapter 316, keyboard and mouse adapter 320, modem 322, read
only memory (ROM) 324, hard disk drive (HDD) 326, CD-ROM driver
330, universal serial bus (USB) ports and other communications
ports 332, and PCI/PCIe devices 334 connect to ICH 310. PCI/PCIe
devices may include, for example, Ethernet adapters, add-in cards,
PC cards for notebook computers, etc. PCI uses a card bus
controller, while PCIe does not. ROM 324 may be, for example, a
flash binary input/output system (BIOS). Hard disk drive 326 and
CD-ROM drive 330 may use, for example, an integrated drive
electronics (IDE) or serial advanced technology attachment (SATA)
interface. A super I/O (SIO) device 336 may be connected to ICH
310.
An operating system runs on processor 302 and coordinates and
provides control of various components within data processing
system 300 in FIG. 3. The operating system may be a commercially
available operating system such as the Microsoft.RTM. Windows.RTM.
XP operating system (Microsoft and Windows are trademarks of
Microsoft Corporation in the United States, other countries, or
both). An object oriented programming system, such as the Java.TM.
programming system, may run in conjunction with the operating
system and provides calls to the operating system from Java.TM.
programs or applications executing on data processing system 300
(Java is a trademark of Sun Microsystems, Inc. in the United
States, other countries, or both).
Instructions for the operating system, the object-oriented
programming system, and applications or programs are located on
storage devices, such as hard disk drive 326, and may be loaded
into main memory 304 for execution by processor 302. The processes
of the present invention are performed by processor 302 using
computer implemented instructions, which may be located in a memory
such as, for example, main memory 304, memory 324, or in one or
more peripheral devices 326 and 330.
Those of ordinary skill in the art will appreciate that the
hardware in FIGS. 1-3 may vary depending on the implementation.
Other internal hardware or peripheral devices, such as flash
memory, equivalent non-volatile memory, or optical disk drives and
the like, may be used in addition to or in place of the hardware
depicted in FIGS. 1-3. Also, the processes of the present invention
may be applied to a multiprocessor data processing system. As some
illustrative examples, data processing system 300 may be a personal
digital assistant (PDA), which is configured with flash memory to
provide non-volatile memory for storing operating system files
and/or user-generated data.
A bus system may be comprised of one or more buses, such as system
bus 206, I/O bus 212 and PCI buses 216, 226 and 228 as shown in
FIG. 2. Of course the bus system may be implemented using any type
of communications fabric or architecture that provides for a
transfer of data between different components or devices attached
to the fabric or architecture. A communications unit may include
one or more devices used to transmit and receive data, such as
modem 218 or network adapter 220 of FIG. 2 or modem 322 or LAN 312
of FIG. 3. A memory may be, for example, local memory 209 or cache
such as that found in memory controller/cache 208 of FIG. 2 or main
memory 304 of FIG. 3. A processing unit may include one or more
processors or central processing units, such as processor 202 or
processor 204 of FIG. 2 or processor 302 of FIG. 3. The depicted
examples in FIGS. 1-3 and above-described examples are not meant to
imply architectural limitations. For example, data processing
system 300 also may be a tablet computer, laptop computer, or
telephone device in addition to taking the form of a PDA.
FIG. 4 is a pictorial representation of a login screen in
accordance with an exemplary embodiment of the present invention.
The login screen is designated by reference number 400. Login
screen 400 comprises input location 402 for inputting the user's
primary ID, input location 404 for inputting the user's password
for the user's primary ID, the primary password, input location 406
for inputting the user's secondary ID, and input location 408 for
inputting the user's password for the user's secondary ID, the
secondary password. While FIG. 4 depicts a login screen capable of
accepting two different user IDs and passwords, those skilled in
the art will realize that the screen could be modified to accept
any number of user IDs and passwords. The depiction of a login
screen capable of accepting two different user IDs and passwords is
shown to illustrate exemplary aspects of the present invention but
is not meant to imply any specific limitations on the
invention.
FIG. 5 is a block diagram of a login system in accordance with an
exemplary embodiment of the present invention. The login system is
designated by reference number 500. Login information 502 comprises
the users' primary and secondary IDs and passwords. Login
information 502 is input into login shell 506 via an input screen,
such as input screen 400 in FIG. 4. Login shell 506 is part of
operating system (OS) 504. Login shell 506 communicates with user
database 514 to obtain multi-user credentials 516.
User credentials comprise the user's ID and the user's primary
group ID and any secondary group IDs. Multi-user credentials
comprise a set of multiple user credentials for one individual
user. In the present example, multi-user credentials 516 comprise
the user's primary and secondary IDs and the user's primary and
secondary group IDs. In the case of multi-user credentials, the set
of secondary group IDs comprises the user's set of secondary group
IDs for the user's primary ID, the primary group ID of the user's
secondary ID, and the set of secondary group IDs for the user's
secondary ID. In order to avoid security issues, the scope of
multi-user credentials 516 is the life of login shell 506. While
multi-user credentials 516 have been described in terms of
comprising a primary user credential and a secondary user
credential, multi-user credentials 516 could comprise any number of
additional credentials belonging to the user.
A request for file access, along with multi-user credentials 516,
is sent to file/directory access checking 510, which is part of
file server 508. File/directory access checking 510 communicates
with file storage 512 to verify multi-user credentials 516.
File/directory access checking 510 sends a response either granting
or denying access back to OS 504 depending on the result of the
outcome of the verification.
In another exemplary embodiment, user database 514 and file store
512 may be a single entity. In a further embodiment, user data base
514 may be accessed through file server 508 instead of directly by
OS 504, as depicted.
FIG. 6 is a block diagram that illustrates communicating a remote
command between two data processing systems in accordance with a
preferred embodiment of the present invention. Local data
processing system 602 communicates with remote data processing
system 604 via communications link 606. Local data processing
system 602 and remote data processing system 604 may be implemented
as a server data processing system, such as server 104 in FIG. 1, a
client data processing system, such as client 108 in FIG. 1,
processes executing on the same computer or any combinations
thereof. Those skilled in the art will realize that communications
link 606 comprises many types of communication links including, but
not limited to, a network, wireless communication, direct link, or
software which makes remote data processing system 604 appear to be
a remote system even when it is resident on the same data
processing system as local data processing system 602.
FIG. 7 is a flowchart illustrating operation of file/directory
access checking in accordance with exemplary aspects of the present
invention. The operation of file/directory access checking is
designated by reference number 700. Operation begins when the
file/directory access checker, such as file/directory access
checker 510 in FIG. 5, receives multi-user credentials, such as
multi-user credentials 516 in FIG. 5, (step 702). A determination
is made as to whether or not the file user ID matches the user's
primary ID (step 704). If the file user ID does match the user's
primary ID (a yes output from step 704), then the user permissions
are checked (step 706) and operation ends. In the present example,
it is presumed that there is only one owner of a file. The user ID
of the owner is known as the file user ID. Therefore, once it has
been determined that the user's primary ID matches the file user
ID, there is no need to check any further as no other user ID can
match the file user ID.
If the file user ID does not match the user's primary ID (a no
output from step 704), then a determination is made as to whether
or not the file user ID matches the user's secondary ID (step 708).
If the file user ID does match the user's secondary ID (a yes
output from step 708), then the user permissions are checked (step
706) and operation ends. If the file user ID does not match the
user's secondary ID (a no output from step 708), a determination is
made as to whether or not the file group ID matches the user's
primary group ID (step 710).
If the file group ID does match the user's primary group ID (a yes
output from step 710), then the user group permissions are checked
(step 712) and operation ends. In the present example, it is
presumed that, like with the file user ID, there is only one group
ID for a file. Therefore, once it has been determined that the
user's primary group ID matches the file group ID, there is no need
to check any further as no other group ID can match the file group
ID.
If the file group ID does not match the user's primary group ID (a
no output from step 710), a determination is made as to whether or
not the file group ID matches any of the user's secondary group IDs
(step 714). The user's secondary group ID comprises of all
secondary group IDs of the user's primary ID and all group ID of
the user's secondary ID. If the file group ID does match one of the
user's secondary group IDs (a yes output from step 714), then the
user group permissions are checked (step 712) and operation ends.
If the file group ID does not match one of the user's secondary
group IDs (a no output from step 714), then other permissions are
checked (step 716) and operation ends.
In an alternative embodiment, instead of checking for permissions
and ending once a match for the file user ID has been found,
operation continues by checking the file group ID against the
multi-user credentials in order to find any matching group IDs.
These two sets are compared and the user is granted the most
permissive set of permissions of the two sets of permissions.
Alternatively, the user could be granted the integrated set of
permissions. In another embodiment, the user is granted the least
permissive set of permissions of the two sets of permissions.
Alternatively the user is granted access only based on those
permissions that are common to both the sets of permissions
While the examples detailed above have been described in terms of a
system where there is only one file user ID and one file group ID
for each file, one of ordinary skill in the art will recognize that
the above detailed operation can apply to other implementations
where there are more than one file user ID and file group ID
associated with a file. In such cases, the file/directory access
checking may operate as described, stopping after identifying a
single instance of matching. In an alternate embodiment, the
operation may be modified to check all of the multi-user
credentials to determine all the matching IDs and permissions. In
one embodiment, the user could then be granted the broadest, or
most permissive, set of allowed permission to the files. All the
permissions allowed to the multi-user credential are integrated and
the user is granted the set of all the allowed, integrated
permissions. In another embodiment, to ensure security, the user is
granted the narrowest, or least permissive, set of allowed
permissions. In one embodiment, all the permissions granted to the
multi-user credentials are compared and the user is denied access
based on the permissions belonging to the ID with the least
permissions. Alternatively, all the permissions granted to the
multi-user credentials could be compared and the user may be
granted only those permissions that are common to all the IDs that
have been granted access.
In another embodiment, once the multi-user credentials have been
verified and access granted, the data processing system, such as
local data processing system 602 in FIG. 6, may issue a command to
a remote data processing system, such as remote data processing
system 604 in FIG. 6. In an alternate embodiment, instead of the
local data processing system verifying the multi-user credentials,
the remote command along with the multi-user credentials may be
transmitted to the remote data processing system, wherein the
remote data processing system verifies the multi-user credentials
and executes the remote command, pending the outcome of the
verification.
FIG. 8 is a flowchart illustrating operation of executing a command
on a remote data processing system in accordance with exemplary
aspects of the present invention. The operation of executing a
remote command is designated by reference number 800 and begins
when the local data processing system sends a remote command to a
remote data processing system along with the primary user
credentials (step 802). A determination is made as to whether or
not access is granted (step 804). The determination may be based on
a reply from the remote data processing system explicitly granting
or denying access or other indicators may be used depending upon
the implementation. If access is granted (a yes output from step
804), the local system receives the results of the remote command
(step 806) and ends. The results of the remote command may take
many forms including results of the executed command, a
notification that the command was executed, or other indicators,
depending upon the particular implementation.
If access is denied (a no output from step 804), the local data
processing system sends the remote command to the remote data
processing system along with the secondary user credentials (step
808). A determination is made as to whether or not access is
granted (step 810). If access is granted (a yes output from step
810), the local system receives the results of the remote command
(step 806) and ends. If access is denied (a no output from step
810), the user is notified that access to the remote system is
denied (step 812) and operation ends.
It is important to note that while the above operation is described
in terms of checking two sets of user credentials, primary and
secondary, those of ordinary skill in the art will recognize that
executing a remote command with multi-user credentials can be
modified to continue sending the remote command to the remote data
processing system coupled with other user credentials, continuing
the process until all the credentials that a user possesses have
been checked for access.
The invention can take the form of an entirely hardware embodiment,
an entirely software embodiment or an embodiment containing both
hardware and software elements. In an exemplary embodiment, the
invention is implemented in software, which includes but is not
limited to firmware, resident software, microcode, etc.
Furthermore, the invention can take the form of a computer program
product accessible from a computer-usable or computer-readable
medium providing program code for use by or in connection with a
computer or any instruction execution system. For the purposes of
this description, a computer-usable or computer readable medium can
be any apparatus that can contain, store, communicate, propagate,
or transport the program for use by or in connection with the
instruction execution system, apparatus, or device.
The medium can be an electronic, magnetic, optical,
electromagnetic, infrared, or semiconductor system (or apparatus or
device) or a propagation medium. Examples of a computer-readable
medium include a semiconductor or solid state memory, magnetic
tape, a removable computer diskette, a random access memory (RAM),
a read-only memory (ROM), a rigid magnetic disk and an optical
disk. Current examples of optical disks include compact disk--read
only memory (CD-ROM), compact disk--read/write (CD-R/W) and digital
video disk (DVD).
A data processing system suitable for storing and/or executing
program code will include at least one processor coupled directly
or indirectly to memory elements through a system bus. The memory
elements can include local memory employed during actual execution
of the program code, bulk storage, and cache memories which provide
temporary storage of at least some program code in order to reduce
the number of times code must be retrieved from bulk storage during
execution.
Input/output or I/O devices (including but not limited to
keyboards, displays, pointing devices, etc.) can be coupled to the
system either directly or through intervening I/O controllers.
Network adapters may also be coupled to the system to enable the
data processing system to become coupled to other data processing
systems or remote printers or storage devices through intervening
private or public networks. Modems, cable modem and Ethernet cards
are just a few of the currently available types of network
adapters.
The description of the present invention has been presented for
purposes of illustration and description, and is not intended to be
exhaustive or limited to the invention in the form disclosed. Many
modifications and variations will be apparent to those of ordinary
skill in the art. The embodiment was chosen and described in order
to best explain the principles of the invention, the practical
application, and to enable others of ordinary skill in the art to
understand the invention for various embodiments with various
modifications as are suited to the particular use contemplated.
* * * * *